Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

The present invention provides a display panel with a flat plate in which
a member partially provided with a light blocking part is disposed in
front of a display panel, and a curable resin therebetween is
sufficiently cured even in an area behind the light blocking part. The
display panel with a flat plate of the present invention includes: a flat
plate provided with a light passing part and a light blocking part; a
display panel; and an adhesive layer between the flat plate and the
display panel, the adhesive layer being a cured resin layer obtainable by
polymerization involving at least one reactive component selected from
the group consisting of a (meth)acrylate oligomer, a bicyclic
ring-containing (meth)acrylate monomer, and a hydroxyl group-containing
(meth)acrylate monomer, a peroxide component, and a primer as reaction
materials.

Claims:

1. A display panel with a flat plate, comprising: a flat plate provided
with a light passing part and a light blocking part; a display panel; and
an adhesive layer between the flat plate and the display panel, the
adhesive layer being a cured resin layer formed by polymerization
involving at least one reactive component selected from the group
consisting of a (meth)acrylate oligomer, a bicyclic ring-containing
(meth)acrylate monomer, and a hydroxyl group-containing (meth)acrylate
monomer, a peroxide component, and a primer as reaction materials.

2. The display panel with a flat plate according to claim 1, wherein the
adhesive layer is a cured resin layer adhering the flat plate and the
display panel.

3. The display panel with a flat plate according to claim 1, wherein an
intermediate member is disposed between the flat plate and the display
panel, and the adhesive layer is a cured resin layer adhering the display
panel and the intermediate member.

4. The display panel with a flat plate according to claim 3, wherein the
intermediate member is a touch panel.

5. The display panel with a flat plate according to claim 1, wherein the
primer comprises a metal complex containing at least one element selected
from the group consisting of iron, aluminum, cobalt, manganese, tin,
zinc, vanadium, chrome, zirconium, indium, and titanium.

6. The display panel with a flat plate according to claim 1, wherein the
reactive component comprises all of the (meth)acrylate oligomer, the
bicyclic ring-containing (meth)acrylate monomer, and the hydroxyl
group-containing (meth)acrylate monomer.

7. The display panel with a flat plate according to claim 1, wherein an
area of the cured resin layer behind the light passing part is formed by
polymerization involving the reactive component and a photopolymerization
initiator as reaction materials.

8. The display panel with a flat plate according to claim 7, wherein the
photopolymerization initiator is present at a lower concentration in the
area of the cured resin layer behind the light passing part of the flat
plate than in an area of the cured resin layer behind the light blocking
part of the flat plate.

9. The display panel with a flat plate according to claim 1, wherein the
primer is present at a higher concentration in the area of the cured
resin layer behind the light passing part of the flat plate than in the
area of the cured resin layer behind the light blocking part of the flat
plate.

10. The display panel with a flat plate according to claim 1, wherein the
cured resin layer is formed substantially only by polymerization
involving the reactive component, the peroxide component, and the primer
as reaction materials.

11. The display panel with a flat plate according to claim 1, wherein the
cured resin layer has a storage modulus at 25.degree. C. of not less than
1.1 kPa.

12. The display panel with a flat plate according to claim 1, wherein the
display panel is a liquid crystal display panel comprising substrates and
a liquid crystal layer between the substrates.

13. The display panel with a flat plate according to claim 1, wherein the
flat plate is a panel that allows for display of a plurality of images on
the display panel at once.

14. A method for producing a display panel with a flat plate including a
flat plate provided with a light passing part and a light blocking part,
a display panel, and an adhesive layer between the flat plate and the
display panel, the method comprising the steps of: charging a primer
between the light blocking part of the flat plate and the display panel;
charging an uncured resin composition containing at least one reactive
component selected from the group consisting of a (meth)acrylate
oligomer, a bicyclic ring-containing (meth)acrylate monomer, and a
hydroxyl group-containing (meth)acrylate monomer, and a peroxide
component into a space between the flat plate and the display panel and
applying the composition onto the primer; and curing the uncured resin
composition on the primer, thereby providing a cured resin layer serving
as an adhesive layer.

15. The method for producing a display panel with a flat plate according
to claim 14, further comprising the step of attaching the flat plate and
the display panel through the uncured resin composition.

16. The method for producing a display panel with a flat plate according
to claim 14, further comprising the steps of: disposing an intermediate
member between the flat plate and the display panel; and attaching the
display panel and the intermediate member through the uncured resin
composition.

17. The method for producing a display panel with a flat plate according
to claim 16, wherein the intermediate member is a touch panel.

18. The method for producing a display panel with a flat plate according
to claim 14, wherein the primer comprises a metal complex containing at
least one element selected from the group consisting of iron, aluminum,
cobalt, manganese, tin, zinc, vanadium, chrome, zirconium, indium, and
titanium.

19. The method for producing a display panel with a flat plate according
to claim 14, wherein the reactive component comprises all of the
(meth)acrylate oligomer, the bicyclic ring-containing (meth)acrylate
monomer, and the hydroxyl group-containing (meth)acrylate monomer.

20. The method for producing a display panel with a flat plate according
to claim 14, wherein an area of the cured resin layer behind the light
blocking part of the flat plate is formed by polymerization initiated by
radicals produced in the reaction of the primer and the peroxide
component.

21. The method for producing a display panel with a flat plate according
to claim 14, further comprising, after the forming of an area of the
cured resin layer behind the light blocking layer of the flat plate, the
step of: emitting light in such a manner that the light passes through
the light passing part of the flat plate, thereby forming an area of the
cured resin layer behind the light passing part of the flat plate.

22. The method for producing a display panel with a flat plate according
to claim 14, wherein the uncured resin composition comprises a
photopolymerization initiator, and the area of the cured resin layer
behind the light passing part of the flat plate is formed by
polymerization initiated by radicals produced by the photopolymerization
initiator in response to light irradiation.

23. The method for producing a display panel with a flat plate according
to claim 14, further comprising the step of precuring the area of the
uncured resin composition behind the light blocking layer of the flat
plate by emitting light towards the space between the flat plate and the
display panel.

24. The method for producing a display panel with a flat plate according
to claim 14, wherein the cured resin layer is formed substantially only
by polymerization involving the reactive component, the peroxide
component, and the primer as reaction materials.

25. The method for producing a display panel with a flat plate according
to claim 14, wherein the display panel is a liquid crystal display panel
comprising substrates and a liquid crystal layer between the substrates.

26. The method for producing a display panel with a flat plate according
to claim 14, wherein the flat plate is a panel that allows for display of
a plurality of images on the display panel at once.

27. A resin composition applied to a base member comprising a light
passing part and a light blocking part to adhere the base member to
another base member, the resin composition being a composition that
comprises at least one reactive component selected from the group
consisting of a (meth)acrylate oligomer, a bicyclic ring-containing
(meth)acrylate monomer, and a hydroxyl group-containing (meth)acrylate
monomer, and a peroxide component, and is cured by a chemical reaction
involving a primer.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a display panel with a flat plate,
a method for producing a display panel with a flat plate, and a resin
composition. Specifically, the present invention relates to a display
panel with a flat plate that is provided for display surface protection,
crack resistance especially in the case of a large display surface, or
aesthetic or other purposes, a method for producing such a display panel
with a flat plate, and a resin composition with which the production
method is practicable.

BACKGROUND ART

[0002] Display panels such as liquid crystal display panels are now used
in a wide application range from business to household applications. So
far, display panels of various sizes, specifically from a small size for
mobile phones, game machines, or the like to a large size for
televisions, outdoor information displays, or the like, have been
fabricated, and practically used.

[0003] In recent years, display panels having an additional function, for
example, capable of displaying three-dimensional (3D) images as well as
conventional two-dimensional (2D) images, or providing images that change
with the viewing angle, have been attracting attention. In some of these
devices, a member for providing such an additional function is disposed
in front of a conventional display panel.

[0004] In particular, some liquid crystal display panels for certain
usages, which include thin glass substrates for a thinner design, are
provided with a glass plate or a transparent plastic plate in front
thereof for the purposes of, for example, display panel surface
protection and crack resistance especially in the case of a large display
panel. Another purpose of such a glass plate disposed in front of a
display panel is to build a model that meets the need for a display
design with a hard, glaring, and flat surface.

[0005] In a conventional model, such a plate (referred to as "flat
plate"), specifically, a glass plate, aplastic plate, a 3D panel, or the
like is disposed in front of a liquid crystal display panel with a
certain space from the liquid crystal display panel surface to which a
polarizer is provided. Such a space, however, is a cause of surface
reflection at the refractive index interface between the liquid crystal
display panel side (inner) surface of the flat plate and air or at the
refractive index interface between the polarizer and air. This also
causes problems such as double exposure images or reflection of an image
that interferes with displayed images. These problems are attributed to
the difference in refractive index between substances, and therefore can
be solved by forming an antireflection coat on the surfaces at which
reflection occurs, or replacing the air layer with a material having a
refractive index close to that of the flat plate or the polarizer. These
techniques can be seen in the case that a resin is filled in a space
between a liquid crystal display panel and a flat plate (see Patent
Literature 1) or in the case that a plasma panel and a flat plate is
adhered by a resin disposed therebetween (see Patent Literature 2).

[0006] As other examples of improved display panels with a flat plate,
there may be mentioned a display panel in which a flat plate is adhered
using a resin having an elastic modulus after cure of not lower than a
certain value to avoid stress that is generated when the resin is cured
and shrinks, and may form streaks on the display (see Patent Literature
3), and in the case that a flat plate and a liquid crystal display panel
are adhered together with a photocurable resin that is enclosed in a
dam-like structure surrounded by a guide between the flat plate and the
liquid crystal display panel (see Patent Literature 4).

[0007] When a flat plate is attached to a display panel by charging a
photocurable resin composition in a space between the flat plate and the
display panel, and photocuring the resin, there is the following
disadvantage. For example, in the case where there is apart that blocks
light, the light blocking part prevents a sufficient amount of light from
reaching the entire resin, and therefore leaves apart of the resin
uncured. One strategy to overcome this disadvantage is that the
photocurable resin is cured by light irradiation from the outside to a
lateral face to certainly allow even an area of the photocurable resin
composition behind the light blocking part to be cured (see Patent
Literatures 5 and 6). Another strategy to cure the area of the
photocurable resin composition behind the light blocking part is to use a
thermal polymerization initiator to allow the resin to be cured not only
by photopolymerization but also by thermal polymerization (see Patent
Literature 7). Use of both photopolymerization and thermal polymerization
regardless the presence or absence of light blocking parts is also under
development (see Patent Literature 8).

CITATION LIST

Patent Literature

[0008] Patent Literature 1: JP-A 2005-55641

[0009] Patent Literature 2:
JP-A 2007-94191

[0010] Patent Literature 3: JP-A 2008-282000

[0011]
Patent Literature 4: JP-A 2008-129159

[0012] Patent Literature 5: JP-A
2009-186954

[0013] Patent Literature 6: JP-A 2009-186955

[0014] Patent
Literature 7: JP-A 2008-281997

[0015] Patent Literature 8: JP-A
2010-26539

SUMMARY OF INVENTION

Technical Problem

[0016] Alternatively, in order to adhere a flat plate to a display panel
using a photocurable resin, the photocurable resin may be cured by light
irradiation from two directions, namely, from the flat plate side and the
display panel side. However, light irradiation from the liquid crystal
display panel side is not preferable because light is blocked by members
of the liquid crystal display panel such as TFTs, lines, and black
matrix, and attenuated by color filters. Additionally, some display
panels themselves block light. Accordingly, light should be emitted from
the flat plate side, but may be interrupted by a light blocking part of
the flat plate. Then, the strategy disclosed in Patent Literatures 5 and
6 seems to be possible, which involves adhering a flat plate and a
display panel, and curing an uncured resin area behind a light blocking
part by light irradiation from a lateral side. In general, such an area
is thin, and unfortunately, a sufficient amount of light may not reach
the entire area. Even if light reaches the entire area, a long period of
irradiation is required to completely cure the area. Accordingly, this
production process is not suitable. In particular, in the case of a
large-scale display, it is difficult to sufficiently cure an entire area
behind a light blocking part by this strategy.

[0017] An alternative strategy is to thermally cure an entire area behind
a light blocking part. Unfortunately, thermal curing polymerization
generates a shrinkage stress, and further generates a stress due to the
difference in thermal expansion coefficient as the temperature decreases
from a high temperature after the reaction. As a result, a thin glass
plate may bend. In particular, when the thermal curing process is
performed on a large display panel, this problem appears more seriously,
and it is very difficult to suppress these stresses. Another problem is a
property of thermally cured resins, namely, these resins are likely to
lose transparency compared to photocurable resins. Additionally, there
are disadvantages of production steps: thermally-curable resins cannot be
processed at ordinary temperature; and the curing rate of
thermally-curable resins is slower than that of photocurable resins.

[0018] The following illustrates problems of a liquid crystal display
panel in which an uncured area remains. FIGS. 18 and 19 are
cross-sectional views schematically illustrating a flat plate including a
light blocking part and a display panel (to be) subjected to light
irradiation from the flat plate side. FIG. 18 is a view before the light
irradiation, and FIG. 19 is a view after the light irradiation. A general
liquid crystal display panel 120 includes a pair of substrates 121 and
122 (for example, an active matrix substrate and a color filter
substrate) each mainly composed of a glass substrate, and a liquid
crystal layer 123 between the substrates 121 and 122. The substrates 121
and 122 are each provided with a polarizer 125 on the outer surface. When
a flat plate 110 mainly composed of a transparent substrate 111 is
attached to the liquid crystal display panel 120, a photocurable resin
131 is charged between the flat plate 110 and the polarizer 125 on the
liquid crystal display panel 120, and cured by light irradiation from the
flat plate 110 side. Thus, the flat plate 110 and the liquid crystal
display panel 120 are adhered together. The flat plate 110 is partially
provided with a light blocking layer 112 on the liquid crystal display
panel 120 side surface. The light blocking layer 112 covers the periphery
of the liquid crystal display panel 120, and has important functions of,
for example, hiding the peripheral region on which no image is displayed,
and improving the appearance.

[0019] When the liquid crystal display panel 120 is irradiated with light
from the transparent substrate 111 side, the light blocking part 112
unfortunately prevents an area from being exposed to light, and therefore
leaves an uncured area 116. In the flat plate 110, the area covered with
the light blocking layer 112 is referred to as "light blocking part
101b", and the other area that is not covered with the light blocking
layer 112 is referred to as "light passing area 101a". As shown in FIG.
18, the applied resin, which is liquid, is able to conform to the
surfaces and does not cause the substrate to bend. Once the resin is
cured, the resin shrinks to pull the liquid crystal display panel 120
towards the center, as shown in FIG. 19. In the case where the uncured
area 116 is present, the liquid crystal display panel 120 is pulled very
strongly, and bends up towards the resin. This phenomenon is more
apparent when the glass (the transparent substrate of the flat plate) 111
on the surface is thick. Such bending of the glass substrates leads to a
dimensional difference between the panel and the flat plate. The
circumference along the edge of the liquid crystal display panel 120 is
sealed with a seal 124, and the two glass substrates of the liquid
crystal display panel 120 are fixed to each other with the seal 124. To
compensate for the dimensional difference, the end part of the glass
substrate on the flat plate 110 side deforms to be uneven. Consequently,
the thickness of the liquid crystal layer 123 becomes uneven, which
causes display streaks (also referred to as "circumferential streaks")
along the periphery of the display region. Even when no circumferential
streak is observed after cure, display streaks may appear after leaving
the panel standing at a high temperature. This is presumably because
exposure to different temperatures, for example, by performing an aging
process causes a change in the stress distribution. FIG. 20 is a
photograph of a liquid crystal display panel with luminous streaks that
are attributed to uncured resin. In FIG. 20, there are black-and-white
streaks within the area 5 to 10 mm from the edge along the edge of the
display region of the liquid crystal display panel. Another problem of
such an uncured area is that the resin may leak out, and monomer
components of the resin may penetrate into a member (e.g. the polarizer)
at the surface of the display panel, swell the polarizer, and deteriorate
the performance thereof. This problem may lead to light leakage in black
display and poor display quality.

[0020] The present invention was made to overcome the above problems, and
an object of the present invention is to provide a display panel with a
flat plate in which a member partially provided with a light blocking
part is disposed in front of a display panel, and a curable resin
therebetween is sufficiently cured even in an area behind the light
blocking part.

Solution to Problem

[0021] The present inventors studied various ways to prevent an area
behind a light blocking part from remaining uncured, and focused on a
curing method other than photocuring and thermal curing. Specifically, a
primer containing a metal complex is applied to the undersurface of the
light blocking part, and a composition containing a reactive component
such as a polymerizable monomer or oligomer component and a peroxide is
prepared as an adhesive resin. Subsequently, the primer is contacted with
the uncured resin composition, and dispersed into the resin composition
to cause a radical generating reaction with the peroxide. This initiates
polymerization of the reactive component. This mechanism enables the area
of the uncured resin composition behind the light blocking layer to be
cured without the need of light irradiation. This method allows for use
of general photopolymerization curing to the light passing part, which is
not covered with the light blocking layer, and therefore enables the flat
plate and the display panel to be efficiently adhered together in a short
time at ordinary temperature. It should be noted that the above-mentioned
problems occur not only when the flat plate and the display panel are
directly adhered together but also when another member is disposed
between the flat plate and the display panel.

[0022] One possible example of the member between the flat plate and the
display panel is a touch panel. There are several types of touch panels
such as resistive touch panels, capacitive touch panels, and optical
touch panels. The following description is based on representative
examples of resistive touch panels and capacitive touch panels. In the
case of an optical touch panel being used, the touch panel should be
provided with infrared emitting/receiving elements or a surface acoustic
wave oscillator, and a sensor. These members are located at the
circumference of a liquid crystal display panel, and no other members are
disposed as intermediate members between the flat plate and the display
panel.

[0023] A resistive touch panel includes a plurality of base members (glass
members or films made of PET or the like) provided with striped
electrodes made of a transparent conductive film, and the members are
stacked at intervals such that the direction of the electrode of each
member is perpendicular to that of the electrode of the adjacent member
(the X- or Y-axis direction). The touch panel detects the position of a
finger based on a change in resistance caused by touch by the finger in
use.

[0024] A capacitive touch panel includes substrates (made of glass,
plastic, or the like) on which one or more base members (e.g. films) with
electrodes formed by patterning of a transparent conductive film are
attached (in the case that more than two base members are attached
thereon, the extending directions of the electrodes should be
perpendicular to each other). An AC electric field is already applied to
the electrodes, and the panel detects the position of a finger by
measuring a microcurrent that occurs due to a change in capacitance
caused by touch by the finger in use.

[0025] A common feature of these types is one or more base members with
electrodes. This feature may cause a later-described problem when the
base member(s) are attached or set as intermediate member(s) in the front
of the liquid crystal display panel.

[0026] Generally, such base members for resistive touch panels are
arranged at about 0.1-mm intervals. When the base members are adhered
onto a flat plate, or disposed between the flat plate and a liquid
crystal display panel, a light blocking layer (including a line) of the
flat plate blocks light, and leaves a cured area and an uncured area in a
resin adhering the base members. Due to a stress generated at the
boundary between these areas, the base members may deform, and the
thickness of the spaces between the base members may become uneven. This
may affect the sensitivity of the touch panel, or cause electrodes to
contact with each other, and to lose their function. Such deformation may
make the thickness of the resin uneven in an area near the boundary of
the cured area and the uncured area, which can be a cause of distorted
images. This problem is likely to occur when at least one of the base
members is a soft member. In particular, in the case that a film member,
which is softer than glass members, is attached to the liquid crystal
display panel side as well as the flat plate side using a resin, the
probability of the problem is much higher.

[0027] In a general capacitive touch panel, such base members are arranged
without space therebetween, but include a soft member made of PET or the
like, which is provided with electrical lines thereon. When a light
blocking layer blocks light, and leaves a cured area and an uncured area
in a resin, the resin deforms, and the thickness of the resin becomes
uneven, which can be a cause of distorted images.

[0028] The presence of a light blocking part is attributed to the light
blocking layer of the flat plate, an FPC on the touch panel, and a metal
line along the circumference of the touch panel (if present).

[0029] The following description relates to problems attributed to uncured
resin. For example, FIG. 21 is a cross-sectional view schematically
illustrating a touch panel disposed between a flat plate and a liquid
crystal display panel in which an uncured resin area is present. FIGS. 22
and 23 are plan views schematically illustrating a touch panel between a
flat plate and a liquid crystal display panel. FIG. 22 shows the front
surface, and FIG. 23 shows a surface exposed by removing the light
blocking layer.

[0030] As shown in FIGS. 21 to 23, the touch panel 140 is mainly composed
of a transparent substrate 141 made of glass or the like, and provided
with a peripheral line 142 and a flexible print (FPC) substrate 143 in a
peripheral area. In the case that an uncured resin 116 is present as
shown in FIG. 21, the uncured resin 116 flows into the space between the
liquid crystal display panel 120 and the back light unit 151, or into the
back light unit 151, and thus can be a cause of poor display performance.

[0031] Some components of the leaking resin may erode acrylic films,
cyclohexane films, and the like, which are used as TAC films of
polarizers, retardation films, optical films, and the like.

[0032] Even if leaking uncured resin is wiped off, there still remain many
practical restrictions. Specifically, most of widely used photocurable
resins (in particular, UV curable resins) are acrylic resins, and a
solvent may erode other optical films made of an acrylic resin, and
penetrate into a TAC film, which is a base member of a polarizer, in the
case that MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), or
the like is used as the solvent.

[0033] In contrast, the idea of the present inventors makes it possible to
form an adhesive layer adhering a display panel to another member without
leaving an uncured resin area, and therefore reduces the possibility of
the above problem caused by leaking uncured resin. Thus, the present
inventors arrived at the idea for overcoming the above problems, and
completed the present invention.

[0034] Specifically, one aspect of the present invention is a display
panel with a flat plate which includes: a flat plate provided with a
light passing part and a light blocking part; a display panel; and an
adhesive layer between the flat plate and the display panel, the adhesive
layer being a cured resin layer formed by polymerization involving at
least one reactive component selected from the group consisting of a
(meth)acrylate oligomer, a bicyclic ring-containing (meth)acrylate
monomer, and a hydroxyl group-containing (meth)acrylate monomer, a
peroxide component, and a primer as reaction materials. The following
description is offered to illustrate a display panel with a flat plate of
the present invention in more detail.

[0035] The display panel with a flat plate of the present invention
includes a flat plate provided with a light passing part and a light
blocking part, and a display panel. The position of the light blocking
part can be changed according to the intended use of the display panel,
and thus is not limited at all. The flat plate is provided with both a
light passing part and a light blocking part, and allows a viewer to see
the display panel through the light passing part. The light blocking part
may be, for example, a printed black film formed along the periphery of
the display region to hide the peripheral region, or a printed black film
in a stripe pattern for producing images that can be seen as
three-dimensional images with naked eyes or images that change with the
viewing position. Specifically, one preferable example of the flat plate
is a panel that allows for display of a plurality of images on the
display panel at once. This allows for display of, for example,
three-dimensional (3D) images or images that change with the viewing
angle.

[0036] The display panel with a flat plate of the present invention
includes an adhesive layer between the flat plate and the display panel,
and the adhesive layer is a cured resin layer formed by polymerization
involving at least one reactive component selected from the group
consisting of a (meth)acrylate oligomer, a bicyclic ring-containing
(meth)acrylate monomer, and a hydroxyl group-containing (meth)acrylate
monomer, a peroxide component, and a primer as reaction components.
Preferably, the reactive component includes all of the (meth)acrylate
oligomer, the bicyclic ring-containing (meth)acrylate monomer, and the
hydroxyl group-containing (meth)acrylate monomer. Additionally, in the
present invention, at least an area of the adhesive layer behind the
light blocking part of is formed of a polymer produced by polymerization
of the reactive component which is initiated by radicals produced in the
reaction of the peroxide and the primer. The area other than the area
behind the light blocking part may also be cured by the same mechanism.

[0037] The term "(meth)acrylate oligomer" refers to oligomers having at
least one (meth)acrylate group at a terminal or in a side chain, and
examples thereof include polyisopropylene(meth)acrylate,
polybutadiene(meth)acrylate, urethane(meth)acrylate, epoxy(meth)acrylate,
polyester(meth)acrylate, and melamine(meth)acrylate. Specific examples of
commercial products thereof include UC-1 (product of KURARAY CO., LTD.,
polyisoprene(meth)acrylate) and TE-2000 (product of Nippon Oil
Corporation, polybutadiene(meth)acrylate).

[0043] The present invention enables at least an area behind a light
blocking part to be cured into a cured resin layer without performing
photocuring and thermal curing, ensures sufficient curing, and can avoid
the problems caused by conventional methods such as light irradiation
from a lateral side or heating.

[0044] In the case that an intermediate member is disposed between the
flat plate and the display panel, the adhesive layer of the display panel
with a flat plate of the present invention may be a layer adhering the
intermediate member with the flat plate or the display panel.
Specifically, the following structures can be mentioned as examples of
the structure of the display panel with a flat plate of the present
invention: (i) the adhesive layer is a cured resin layer adhering the
flat plate and the display panel; and (ii) an intermediate member is
disposed between the flat plate and the display panel, and the adhesive
layer is a cured resin layer adhering the display panel and the
intermediate layer. The number of the intermediate members is not limited
at all.

[0045] The structure of the display panel with a flat plate of the present
invention is not particularly limited by other members as long as it
includes these essential members.

[0046] The following description is offered to illustrate preferable
embodiments of the display panel with a flat plate of the present
invention in detail.

[0047] An area of the cured resin layer behind the light passing part of
the flat plate is preferably formed by polymerization involving the
reactive component and a photopolymerization initiator as reaction
materials. Such photopolymerization using a photopolymerization initiator
provides a cured resin layer having a high transmissivity, and therefore
ensures good visibility of the display panel. Additionally, the
photopolymerization using a photopolymerization initiator can proceed at
ordinary temperature unlike thermal polymerization, and establishes
adhesion more rapidly (in several minutes to several hours) than use of
an adhesive, and thus is advantageous in terms of cycle time. An
essential feature of the present invention lies in that the area behind
the light blocking area is formed by polymerization involving the
reactive component, the peroxide component, and the primer, and this
embodiment ensures better reactivity and visibility of the light passing
part.

[0048] Alternatively, the cured resin layer is preferably formed
substantially only by polymerization involving the reactive component,
the peroxide component, and the primer as reaction materials. This
embodiment can be usable, for example, in the case that no limit is
imposed on the production time, or in the case that photopolymerization
is not suitable because the area of the light blocking part is much
larger than the area of the light passing part.

[0049] The cured resin layer preferably has a storage modulus at
25° C. of not less than 1.1 kPa. If the storage modulus after cure
of the cured resin layer is lower than 1.1 kPa, the resin is flowable,
and may fail to sufficiently fix the members, and cause display streaks.
In order to ensure reliability, this condition is preferably met.

[0050] The display panel is preferably a liquid crystal display panel
including substrates and a liquid crystal layer between the substrates.
In particular, in the case of a liquid crystal display panel, an uncured
area, if present, behind the light blocking part can cause display
streaks, as described above. To avoid this, the present invention is
suitable for liquid crystal display panels.

[0051] The flat plate is preferably a panel that allows for display of a
plurality of images on the display panel at once. Examples of such panels
include a panel that allows for display of three-dimensional images and a
panel that allows for display of images that change with the viewing
position.

[0052] In order to produce three-dimensional images, for example, a panel
including a light blocking part having slits may be disposed in front of
or behind the display screen. The light blocking part includes lines
arranged in a stripe pattern, allows for display of different images for
the respective eyes on the display panel at once, and therefore can
display three-dimensional images. Accordingly, the present invention is
particularly suitable for three-dimensional display panels. Specifically,
the flat plate is preferably a three-dimensional display panel that
includes a light blocking part having slits, and is to be disposed in
front of or behind the display screen.

[0053] Alternatively, a light blocking member having slits may be disposed
in front of the display panel to form alight blocking part having a
stripe pattern similarly to that of the above-mentioned three-dimensional
display panel. This panel allows for display of images that change with
the viewing position. This type of light blocking member, which blocks
light and prevents an area from being exposed to light, is suitably used
with the present invention. Thus, the flat plate is preferably a panel
capable of producing images that change with the viewing position.

[0054] In particular, in the case that the intermediate member includes a
light blocking member that is disposed to be behind the light blocking
part of the flat plate, the present invention is suitably used. In this
case, the light blocking member may block light and leave an uncured area
even when light is emitted from the side opposite to the light blocking
part of the flat plate. The method using the reactive component, however,
enables an area which light does not reach to be cured, and thus prevents
a problem of leakage of uncured resin to other areas. Examples of such as
intermediate members include touch panels. A general touch panel includes
peripheral lines that block light and an FPC substrate outside a display
region (the region overlapping the light passing part of the flat plate).

[0055] The present invention further relates to a method for producing
such a display panel with a flat plate. Specifically, another aspect of
the present invention is a method for producing a display panel with a
flat plate including a flat plate provided with a light passing part and
a light blocking part, a display panel, and an adhesive layer between the
flat plate and the display panel, the method including the steps of:
charging a primer between the light blocking part of the flat plate and
the display panel; charging an uncured resin composition containing at
least one reactive component selected from the group consisting of a
(meth)acrylate oligomer, a bicyclic ring-containing (meth)acrylate
monomer, and a hydroxyl group-containing (meth)acrylate monomer, and a
peroxide component into a space between the flat plate and the display
panel and applying the composition onto the primer; and curing the
uncured resin composition on the primer, thereby providing a cured resin
layer serving as an adhesive layer. Preferably, the reactive component
includes all of the (meth)acrylate oligomer, the bicyclic ring-containing
(meth)acrylate monomer, and the hydroxyl group-containing (meth)acrylate
monomer.

[0056] The curing using the primer causes curing only in an area near the
area to which the primer is applied, and this means that it is possible
to determine any area as an area to be cured unlike thermal curing by
which it is difficult to cure only a limited area. The present invention
allows an area which light emitted from the flat plate side does not
reach to be cured by the action of the primer, and therefore does not
leave an uncured area. Accordingly, the area of the cured resin layer
behind the light blocking part of the flat plate is preferably formed by
polymerization involving radicals generated by the reaction of the primer
and the peroxide component.

[0057] Additionally, the curing using the primer allows for curing at
around room temperature, and therefore allows the resin composition to be
cured without generating a stress therein unlike thermal curing involving
heating to a high temperature. Thus, it is possible to prevent streaks
attributed to stress.

[0058] The method for producing a display panel with a flat plate of the
present invention is not particularly limited by other production steps
as long as it includes these essential production steps. As specific
examples of the reactive component, the peroxide component, and the
primer used in the production method of the present invention, there may
be mentioned the same examples listed for the display panel with a flat
plate of the present invention.

[0059] In the method for producing a display panel with a flat plate of
the present invention, the adhesive layer is not limited to a layer
adhering the flat plate and the display panel. In the case that an
intermediate member is disposed between the flat plate and the display
panel, the adhesive layer may be a layer adhering the display panel and
the intermediate member.

[0060] Specifically, the method for producing a display panel with a flat
plate of the present invention may further include the step of: (i)
attaching the flat plate and the display panel through the uncured resin
composition; or (ii) disposing an intermediate member between the flat
plate and the display panel, and attaching the display panel and the
intermediate member through the uncured resin composition as the adhesive
layer.

[0061] The following description is offered to illustrate a preferable
embodiment of the method for producing a display panel with a flat plate
of the present invention in detail.

[0062] The production method preferably further includes, after the
above-mentioned step of curing the uncured resin on the primer, the step
of emitting light in such a manner that the light passes through the
light passing part of the flat plate, thereby forming a cured resin layer
behind the light passing part of the flat plate. It is preferable that
the light passing part of the display panel is subjected to light
irradiation, which can uniformly treat a wider area in a shorter time,
because the entire area of the display panel is much larger than that of
the light passing part, which corresponds to the display region. This
reduces the cycle time.

[0063] The curing using the primer, which proceeds more slowly than
photocuring, may be allowed to gradually proceed after photocuring. This
makes it possible to alleviate stress concentration caused by shrinkage
around the boundary region of curing in which there are differences in
the physical properties (in particular, shrinkage property) between the
two resin areas caused by curing the resin because the uncured area is
cured to conform to the shrinking shape of the already cured photocurable
area.

[0064] It is preferable that the uncured resin composition contains a
photopolymerization initiator, and an area of the cured resin layer
behind the light passing part of the flat plate is formed by
polymerization initiated by radicals produced by the photopolymerization
initiator in response to light irradiation. This allows for rapid and
sufficient photopolymerization.

[0065] The production method preferably further includes the step of
precuring the area of the uncured resin composition behind the light
blocking part of the flat plate by emitting light towards the space
between the flat plate and the display panel. The precuring prevents the
flat plate and the display panel from moving relative to each other in
the curing using the primer, which proceeds slowly.

[0066] The preferable embodiments of the method for producing a display
panel with a flat plate are described so far. The above-described
preferable embodiments of the display panel with a flat plate can be
applied to the production method to produce the same effects.

[0067] Still another aspect of the present invention is a resin
composition intended to be applied to a base member including a light
passing part and a light blocking part, and adhering the base member to
another base member, the resin composition being a composition that
contains at least one reactive component selected from the group
consisting of a (meth)acrylate oligomer, a bicyclic ring-containing
(meth)acrylate monomer, and a hydroxyl group-containing (meth)acrylate
monomer, and a peroxide component, and is cured by a chemical reaction
involving a primer.

Advantageous Effects of Invention

[0068] When a flat plate partially provided with a light blocking part is
attached to a display panel, the present invention allows an area of a
curable resin behind the light blocking part to be sufficiently cured.

BRIEF DESCRIPTION OF DRAWINGS

[0069] FIG. 1 is a cross-sectional view schematically illustrating a
display panel with a flat plate of embodiment 1;

[0070] FIG. 2 is an enlarged view of a part where the flat plate and the
display panel of embodiment 1 are attached;

[0071] FIG. 3 is a cross-sectional view illustrating a step for attaching
the flat plate and the display panel in embodiment 1;

[0072] FIG. 4 is a cross-sectional view illustrating another step for
attaching the flat plate and the display panel in embodiment 1;

[0073] FIG. 5 is a cross-sectional view illustrating a still another step
for attaching the flat plate and the display panel in embodiment 1;

[0074] FIG. 6 is a cross-sectional view schematically illustrating
polymerization involving a reactive component, a primer, and a peroxide
as reaction materials;

[0075] FIG. 7 is a cross-sectional view schematically illustrating a
display panel with a flat plate of embodiment 2;

[0076] FIG. 8 is a cross-sectional view illustrating a step for attaching
the flat plate and the display panel in embodiment 2;

[0077] FIG. 9 is a cross-sectional view illustrating another step of
attaching the flat plate and the display panel in embodiment 2;

[0078] FIG. 10 is a cross-sectional view illustrating a still another step
of attaching the flat plate and the display panel in embodiment 2;

[0079] FIG. 11 is a cross-sectional view schematically illustrating a
display panel with a flat plate of embodiment 3;

[0080] FIG. 12 is a perspective view schematically illustrating a display
panel with a flat plate of embodiment 4;

[0081] FIG. 13 is a view schematically illustrating a mechanism of a
three-dimensional display panel;

[0082] FIG. 14 is a view schematically illustrating a mechanism of
production of images that differ with the viewing position;

[0083] FIG. 15 is a view schematically illustrating a mechanism of another
three-dimensional display panel;

[0084] FIG. 16 is a graph of adhesion strength vs. time for the case in
which the primer concentration was not diluted;

[0085] FIG. 17 is a graph of adhesion strength vs. time for the case in
which the primer concentration was diluted to 1/10;

[0086] FIG. 18 is a cross-sectional view schematically illustrating a flat
plate with a light blocking part and a display panel before light
irradiation from the flat plate side;

[0087] FIG. 19 is a cross-sectional view schematically illustrating the
flat plate with a light blocking part and the display panel after light
irradiation from the flat plate side;

[0088] FIG. 20 is a photograph of a liquid crystal display panel with
streaks caused by remaining uncured resin.

[0089] FIG. 21 is a cross-sectional view schematically illustrating a
structure in which a touch panel is disposed between a flat plate and a
liquid crystal display panel, and an uncured resin area remains;

[0090] FIG. 22 is a schematic plan view of a front surface of a structure
in which a touch panel is disposed between a flat plate and a liquid
crystal display panel; and

[0091] FIG. 23 is a schematic plan view of a surface exposed by removing
the light blocking layer of the structure in which the touch panel is
disposed between the flat plate and the liquid crystal display panel.

DESCRIPTION OF EMBODIMENTS

[0092] The following embodiments are offered to illustrate the present
invention in more detail with reference to the figures, but are not
intended to limit the present invention.

[0093] The present invention covers display panels with a flat plate
provided with a light blocking part, and the size of the display screen
is not limited at all. The "flat plate" herein is not limited to a single
plate (e.g. a glass plate or a plastic plate) like those described in the
following embodiments. One example of the flat plate is a panel
consisting of two or more plates for producing three-dimensional images.

[0094] The flat plate is disposed in front of (on the display surface side
of) the display panel for the purpose of protection of the front face of
the display panel, but the position of the flat plate is not limited only
to in front of the display panel. For example, in the case that a flat
plate is a three-dimensional panel with slits, and a display panel has
transmissitity, the slits can function even when they are located at
either in front of or behind the display panel.

[0095] In the present invention, other intermediate members such as a
touch panel may be disposed between the flat plate and the display panel
as long as the display panel includes an adhesive layer defined in the
present invention.

[0096] Larger-scale displays often have more apparent circumferential
display streaks. Therefore, the present invention is useful for
large-scale (20 inch or larger) devices, and is suitably used, in
particular, for large-scale displays such as televisions, electric sign
boards, information displays (e.g. electric guide boards in stations and
airports), and digital signage displays. On the other hand, smaller-scale
display panels tend to have a high probability of poor display quality
caused by leakage of uncured resin into a panel. To avoid this in
small-scale (10 inch or smaller) devices, the present invention is also
useful, and specifically, is suitably used for small-scale displays such
as mobile phones and game machines.

[0098] Embodiment 1 provides a display panel with a flat plate in which a
flat plate is disposed in front of a liquid crystal display panel. FIG. 1
is a cross-sectional view schematically illustrating the display panel
with a flat plate of embodiment 1, and FIG. 2 is an enlarged view of a
part where the flat plate and the display panel of embodiment 1 are
attached. As shown in FIG. 1, the flat plate 10 is attached to the
display panel 20 through a cured resin layer 33 in embodiment 1.

[0099] As shown in FIG. 2, the display panel 20 includes a pair of
substrates 21 and 22, and a liquid crystal layer 23 between the
substrates 21 and 22. One of the substrates 21 and 22 is an active matrix
substrate 21, and the other is a color filter substrate 22. The active
matrix substrate 21 is mainly composed of an insulative substrate such as
a glass substrate, and includes members for regulating the alignment of
liquid crystal molecules, such as TFTs, pixel electrodes, and various
lines (e.g. scan lines and signal lines), on the insulative substrate.
Likewise, the color filter substrate 22 is mainly composed of an
insulative substrate such as a glass substrate, and includes members such
as color filters, a black matrix, and a common electrode on the
insulative substrate. A liquid crystal material is enclosed in the space
between the substrates 21 and 22. This space is surrounded by a seal 24,
and a spacer is disposed to secure a certain distance between the
substrates. Each of the substrates 21 and 22 is provided with a polarizer
25 on the outer surface thereof, and these polarizers control light
emitted to the display panel 20 and light proceeding in the display panel
20 to pass therethrough to the outside or to be blocked.

[0100] The flat plate 10 is mainly composed of a transparent substrate 11
made of glass, plastic, or the like, and protects the surface of the
display panel 20. A black matter (light blocking layer) 12 for blocking
light is partially printed on the display panel 20 side surface of the
transparent substrate 11. The flat plate 10 includes a light passing part
1a and a light blocking part 1b. The light blocking part 1b refers to an
area in which a light blocking layer 12 is formed, and the light passing
part 1a refer to the other area. The light passing part 1a substantially
corresponds to a display region, and allows a viewer to see images
produced by the display panel 20. In embodiment 1, the light blocking
layer 12 is located along the edge of the display region (light passing
part) 1a of the display panel 20. The light blocking part 1b hides
peripheral members, such as peripheral circuits, of the display panel 20,
and therefore improves the appearance.

[0101] The cured resin layer 33 is a layer formed by polymerization of at
least one reactive component selected from the group consisting of a
(meth)acrylate oligomer, a bicyclic ring-containing (meth)acrylate
monomer, and a hydroxyl group-containing (meth)acrylate monomer into a
polymer. Preferably, the cured resin layer 33 is formed by using all of
these components. One example of the ratio of these components before
polymerization is 30 to 50 parts by mass of the (meth)acrylate oligomer,
30 to 50 parts by mass of the bicyclic ring-containing (meth)acrylate
monomer, and 10 to 30 parts by mass of the hydroxyl group-containing
(meth)acrylate monomer. A resin composition containing the reactive
component is charged between the flat plate 10 and the display panel 20,
and the predetermined reaction is caused. As a result, the cured resin
layer 33 is formed by polymerization as an adhesive layer adhering the
flat plate and the display panel. When the (meth)acrylate is used, the
resulting polymer can be easily controlled to have high transmissivity
and a refractive index equivalent to that of glass.

[0102] The cured resin layer 33a behind the light passing part 1a is
formed by radical polymerization of the reactive component which is
induced by radicals produced by the photopolymerization initiator in
response to light irradiation from the flat plate 10 side. The cured
resin layer 33b behind the light blocking part 1b is formed by radical
polymerization in which radicals produced by the reaction of the primer
and the peroxide initiate polymerization of the reactive component. The
amount of the peroxide in the resin composition before radical generation
is, for example, 0.5 to 5% by mass relative to 100% by mass of the whole
resin composition. Thus, although the light blocking part 1b inhibits
light irradiation, this method ensures sufficient polymerization without
leaving an uncured area regardless of the presence of the light blocking
part 1b of the flat plate 10. Additionally, the combination of radical
polymerization by light irradiation and radical polymerization involving
the primer and the peroxide does not cause rapid curing shrinkage, and
therefore can avoid variations in size of the display panel with a flat
plate, and ensure high reliability.

[0103] Especially, embodiment 1 ensures good display quality because even
when the substrates of the liquid crystal display panel are large thin
glass substrates, this embodiment prevents the glass substrates from
bending and having a wavy edge, and in turn prevents the thickness of the
liquid crystal layer 23 from becoming uneven, and also prevents display
streaks in the periphery of the display panel. The area of the cured
resin layer behind the light passing part 1a, which is made of a polymer
obtained by photopolymerization, has high transmissivity.

[0104] The thickness of the flat plate 10 is preferably 0.5 to 3 mm. The
thickness of the light blocking layer 12 is preferably 20 μm. The
width of the light blocking layer 12 is preferably 5 to 30 mm although it
depends on the panel size. If the width of the light blocking layer 12 is
more than 1 mm, light emitted from a lateral side does not reach the
entire area behind this layer. The thickness of the cured resin layer is
preferably 50 to 150 μm. The thickness of the insulative substrates
(e.g. glass substrates) of the substrates of the liquid crystal display
panel is preferably 0.5 to 1.1 mm. These ranges are mentioned only as
examples, and are not intended as limitations.

[0105] The following description is offered to illustrate the procedure of
attaching the flat plate and the display panel in embodiment 1 in more
detail. FIGS. 3 to 5 are cross-sectional views each illustrating a step
for attaching the flat plate and the display panel in embodiment 1.

[0107] Next, as shown in FIG. 4, the display panel 20 and the flat plate
10 are aligned such that the end of the display panel 20 overlaps the
light blocking layer 12 of the flat plate 10, the resin composition 30
containing the reactive component 31 and peroxide component 32 is charged
between the display panel 20 and the flat plate 10, and then the flat
plate 10 and the display panel 20 are attached. Once these are attached,
the primer 13 begins to spread into the resin composition 30, and reacts
with the peroxide 32 to produce radicals. Namely, when the flat plate 10
and the display panel 20 are attached, polymerization occurs in the light
blocking part 12. Since the undersurface of the light passing part 1a of
the flat plate 10 is not coated with the primer, only an area of the
resin composition 30 behind the light blocking part 1b, that is, an area
where the primer 13 spreads is cured.

[0108] At the same time as attaching the flat plate 10 and the display
panel 20, light is emitted from a lateral side to the attaching part
between the flat plate 10 and the display panel 20, as shown in FIG. 4.
This light irradiation process is a precuring process to prevent the flat
plate 10 and the display panel 20 from moving relative to each other, and
aims to solidify around the edge surface. Therefore, short-time
irradiation is enough, and this does not cure the entire area of the
resin behind the light blocking layer 12.

[0109] Subsequently, the entire flat plate 10 is irradiated with light at
once from the transparent substrate 11 side, as shown in FIG. 5. This is
final curing. Light passing through the light passing part of the flat
plate 10 reaches the resin composition 30 to initiate photopolymerization
and curing. Since the light blocking part 12 of the flat plate 10 blocks
light, the polymerization is not initiated by the light irradiation in
the area of the resin composition 30 behind the light blocking part 12.

[0110] Thus, the cured resin layer 33 is completed without leaving an
uncured area behind the light passing part 1a and the light blocking part
1b of the flat plate 10.

[0111] The following description is given to illustrate the mechanism of
the polymerization reactions in the above-described steps. FIG. 6 is a
cross-sectional view schematically illustrating the polymerization
reaction involving the reactive component, the primer, and the peroxide
as reaction components.

[0112] As shown in FIG. 6, when the resin composition 30 is contacted with
the area coated with the primer 13, the primer 13 begins to spread into
the resin composition 30 (in the directions of the small arrows in the
figure). The spreading primer 13 reacts with the peroxide 32 in the resin
composition 30 to produce radicals. The radicals initiate polymerization
of the reactive component 31 in the resin composition 30. Since the
primer 13 is applied only to the undersurface of the light blocking part
1b, the curing reaction occurs only in an area behind the light blocking
part 1b. However, the curing reaction does not occur in an area apart
from the light blocking part 1b because the primer 13 does not reach this
area.

[0113] On the other hand, the resin composition 13 contains the
photopolymerization initiator 34, and the photopolymerization initiator
34 produces radicals in response to light irradiation so as to initiate
polymerization of the reactive component 31 in an area around the
radicals, as shown in FIG. 6. Thus, the light irradiation causes
photopolymerization in the area behind the light passing part 1a, but
does not cause polymerization in the area behind the light blocking part
1b because light does not reach this area.

[0114] According to the nature of this mechanism, the concentration of the
photopolymerization initiator in the area of the cured resin layer behind
the light passing part 1a of the cured resin layer is lower than the
photopolymerization initiator concentration in the area of the cured
resin layer behind the light blocking part 1b, and the concentration of
the primer in the area of the cured resin layer behind the light passing
part 1a is higher than the primer concentration in the area of the cured
resin layer behind the light blocking part 1b.

Embodiment 2

[0115] Embodiment 2 is a display panel with a flat plate in which a flat
plate is disposed in front of a liquid crystal display panel. FIG. 7 is a
cross-sectional view schematically illustrating the display panel with a
flat plate of embodiment 2. As shown in FIG. 7, a flat plate 10 is
attached to a display panel 20 through a cured resin layer 33.

[0116] The display panel with a flat plate of embodiment 2, which is
produced by a different method from that of embodiment 1, differs from
that of embodiment 1 in some points such as components remaining in the
cured resin layer, but share the following same basic features: the cured
resin layer 33 does not include an uncured area behind the light passing
part 1a and the light blocking part 1b of the flat plate; and no
complicated process such as heat treatment is required.

[0117] The following description is offered to illustrate the procedure of
attaching the flat plate and the display panel in embodiment 2 in more
detail. FIGS. 8 to 10 are cross-sectional views each illustrating a step
for attaching the flat plate and the display panel in embodiment 2.

[0118] First, as shown in FIG. 8, the display panel 20 and the flat plate
10, which is partially provided with the light blocking layer 12, are
prepared. In embodiment 2, the primer 13 is already applied to the entire
display panel side surface of the flat plate 10 including the area
serving as a light passing part 1a as well as the area serving as a light
blocking part 1b. The same materials as those described in embodiment 1
can be used as the primer 13.

[0119] Next, as shown in FIG. 9, the display panel 20 and the flat plate
10 are aligned such that the end of the display panel 20 overlaps the
light blocking layer 12 of the flat plate 10, the resin composition 30
containing the reactive component 31 and peroxide component 32 is charged
between the display panel 20 and the flat plate 10, and then the flat
plate 10 and the display panel 20 are attached. Once these are attached,
the primer 13 begins to spread into the resin composition 30, and reacts
with the peroxide 32 to produce radicals. Namely, when the flat plate 10
and the display panel 20 are attached, polymerization occurs.

[0120] At the same time as attaching the flat plate 10 and the display
panel 20, light is emitted from a lateral side to the attaching part
between the flat plate 10 and the display panel 20, as shown in FIG. 9.
This light irradiation process is a precuring process to prevent the flat
plate 10 and the display panel 20 from moving relative to each other, and
aims to solidify around the edge surface. Therefore, short-time
irradiation is enough.

[0121] After a certain period of standing, the cured resin layer 33 is
completed without leaving an uncured area behind the light passing part
1a and the light blocking part 1b of the flat plate 10, as shown in FIG.
10. Embodiment 2 does not need multiple step polymerization including
photopolymerization, thermal polymerization, and the like although the
reaction rate in embodiment 2 is slower than that in embodiment 1.
Additionally, the above process can be performed at ambient temperature.

[0122] An appropriate combination of the features of embodiments 1 and 2
described so far is acceptable. Specifically, one possible example is
that the area of the resin composition behind the light blocking part is
likewise cured by polymerization using the primer, but a part of the area
of the resin composition behind the light passing part is cured by
photopolymerization, and the remaining part is cured by polymerization
using the primer or the like.

Embodiment 3

[0123] Embodiment 3 is a display panel with a flat plate of a touch panel
type. FIG. 11 is a cross-sectional view schematically illustrating the
display panel with a flat plate of embodiment 3. As shown in FIG. 11, a
touch panel (intermediate member) 40 is disposed between the flat plate
10 and the liquid crystal display panel 20. The touch panel 40 is
attached to the liquid crystal display panel 20 through a cured resin
layer 33. The cured resin layer 33 can be formed in the same manner as in
embodiment 1 or 2.

[0124] The layer shown in FIG. 11 is an example obtained by curing a resin
composition in the same manner as in embodiment 1. Specifically, the
cured resin layer 33a behind the light passing part 1a is formed by
radical polymerization of the reactive component which is initiated by
radicals produced by the photopolymerization initiator in response to
light irradiation from the flat plate 10 side. The cured resin layer 33b
behind the light blocking part 1b is formed by radical polymerization in
which radicals produced by the reaction of the primer and the peroxide
initiate polymerization of the reactive component.

[0125] The light blocking part of the flat plate prevents the entire area
covered with the light blocking part from being exposed to light, and
leaves uncured resin between the touch panel and the liquid crystal
display panel, and thus may affect the adhesion therebetween unless the
method of embodiment 3 is not used.

[0126] Embodiment 3 does not leave uncured resin, and therefore can avoid
the problem of leakage of uncured resin into the space between the liquid
crystal display panel 20 and the back light unit 51 or into the back
light unit 51. Additionally, it is possible to avoid a problem of
penetration of uncured resin into the periphery of the display region
which may occur when the touch panel is pressed with a finger, and may
cause display streaks in the periphery of the display region.

Embodiment 4

[0127] Embodiment 4 is a display panel with a flat plate in which a flat
plate is disposed in front of a display panel, and allows for display of
a plurality of images on the display panel at once. FIG. 12 is a
perspective view schematically illustrating the display panel with a flat
plate of embodiment 4. As shown in FIG. 12, a black printed layer (light
blocking layer) 62 is formed on the flat plate disposed in front of the
display panel 70, and lengthwise slits are formed in the light blocking
layer 62. Thus, the light blocking layer 62 is constituted by a
peripheral part and lengthwise lines. The spaces between the lengthwise
lines may not be slits, and transparent members may be disposed therein.
The display panel 70 includes a display region 91 and a peripheral region
92, and a large number of fine color filters 72 are provided in the
respective pixels in the display region 91. The color alignment of the
color filters 72 is a stripe alignment of three colors: red (R) 72R;
green (G) 72G; and blue (B) 72B, each color forms a line. In embodiment
4, the number of the colors, and the number and alignment of the color
filters are not limited at all.

[0128] FIG. 13 is a view schematically illustrating a mechanism of a
three-dimensional display panel. FIG. 14 is a view schematically
illustrating a mechanism of production of images that differ with the
viewing position.

[0129] As shown in FIGS. 13 and 14, the flat plate 60 includes a
transparent substrate 61 and light blocking layer 62, and the light
blocking layer 62 are disposed on the display panel side surface of the
transparent substrate 61. The display panel 70 shown in FIG. 14 is a
liquid crystal display panel that includes a pair of transparent
substrates 71 and a liquid crystal layer between the transparent
substrates 71. As shown in FIGS. 13 and 14, a plurality of light blocking
layers 62 is located at certain intervals therebetween when viewed in a
cross-sectional view. The color filters 72 are disposed between the
transparent substrates 71, and may be disposed in front of or behind the
liquid crystal layer.

[0130] The expression "panel that allows for display of a plurality of
images on the display panel at once" herein refers to a panel that
enables a viewer to see specific pixels of the display panel from a
certain viewing angle but does not allow the viewer to see these pixels
from another viewing angle, as shown in FIGS. 13 and 14. In such a panel,
a flat plate provided with lines of light blocking parts is disposed on
the front or back side of the display panel. For example,
three-dimensional panels and panels capable of producing images that
change with the position from which the display panel is seen (also
referred to as "dual view panels") are categorized as this type.

[0131] In order to achieve three-dimensional vision, it is necessary to
create a structure capable of producing images that can be recognized
from at least two viewing points respectively (with a vergence angle),
specifically, a structure that allows the eyes to see an image of pixels
(R pixels) for the right eye and an image of pixels (L pixels) for the
left eye, respectively. If the image for the right eye is viewed with the
left eye, or if the image for the left eye is viewed with the right eye,
the image is seen as a double exposure image. To avoid this, the light
blocking layer and slits of the three-dimensional display panel enable
the eyes to see the pixels for the respective eyes.

[0132] FIG. 13 shows the routes of light from the pixels to the eyes. This
structure allows each eye to see one image and does not allow the eyes to
see the other image for the other eye. In FIG. 13, the pixels R are
pixels for the right eye, and the pixels L are pixels for the left eye.
The members arranged widthwise at intervals are the lengthwise lines
serving as light blocking parts. In order to produce three-dimensional
images, the positions of the slits and the light blocking layers 62 are
determined considering the distance between the left and right eyes such
that the image for the right eye and the image for the left eye are seen
by the respective eyes. The distance between slits is substantially twice
the pixel width, and the width of the light blocking layers 62 is 100 to
150% of the width of the pixels. Generally, the distance between eyes of
human is assumed to be about 60 mm.

[0133] An alternative design is that slits are arranged as if they are
adjusted to a larger distance between the eyes, as shown in FIG. 14. A
display of this design enables a viewer to see a different image from a
different position. As shown in FIG. 14, there are first pixels (pixels
indicated by "1" in FIG. 14) for producing a first image, and second
pixels (pixels indicated by "2" in FIG. 14) for producing a second image
in this design, and the distance between the slits and/or the distance
between the light blocking parts is adjusted to determine positions from
which a different image is seen, in front of the display panel. This type
of display mode is also included in the scope of the panel that allows
for display of a plurality of images on the display panel at once. In
this case, the distance between slits is substantially twice the width of
the pixels, and the width of the light blocking layers 62 is 160 to 180%
of the width of the pixels.

[0134] The example of FIG. 14 does not require a viewer to see the first
pixels and the second pixels with the respective eyes unlike
three-dimensional imaging. The viewer sees the pixels with both eyes.
This means that the viewer at an optimal viewing position sees either the
image of the first pixels or the image of the second pixels.

[0135] Theoretically, in the case of, for example, a transmissive liquid
crystal display panel, the "panel that allows for display of a plurality
of images on the display panel at once" may be disposed in front of or
behind the display panel. Embodiment 4 is an example with two viewing
points, but the number of viewing points may be two or more as long as
the same mechanism works.

[0136] In embodiment 4, the light blocking layers and slits of the panel,
which is disposed in front of (or behind) the display panel having pixels
designed to achieve multiple view points, allow light from certain pixels
to pass through and block light from certain pixels depending on the
viewing position. In embodiment 4, the panel provided with such light
blocking layers is attached to the display panel using a resin
composition of the present invention. In some designs, the width of light
blocking layers having such a function is about 50% to 80% of the width
of pixels, and the light blocking layers prevent light emitted from the
front (or back) side of the display panel from reaching the areas behind
the light blocking layers. Thus, the above-mentioned proportion of the
whole resin composition remains uncured.

[0137] As shown in FIG. 14, in the panel that allows for display of a
plurality of images on the display panel at once, the frame of the lines
may be a wide light blocking part. Such a panel may allow only a much
smaller area of the resin to be cured by light compared to those used as
flat plates for televisions. Therefore, a sufficient level of adhesion
strength for attaching the flat plate may not be achieved in some cases.
When a flat plate provided with such light blocking parts is attached to
a display panel or an intermediate member, the following steps are
performed: a primer is applied to or printed onto the undersurface of the
light blocking parts; the slits are aligned as described in embodiment 1;
the peripheral area (side surfaces) of the resin composition is precured
by light; and the whole resin composition is cured by irradiating the
entire display region with light from the flat plate side to adhere the
flat plate and the display panel or the intermediate member.

[0138] In this case, the primer applied to the undersurface of the light
blocking parts causes the area of the resin composition hidden behind the
light blocking parts to be cured. For example, in the case of a 40-inch
high-vision three-dimensional television, the pixel pitch is about 153
μm, the slit width is about 76 to 120 μm, and the number of slits
is 5760. In such a case, it is difficult to apply the primer for each
line. The primer may be applied by printing using a mask or the like.
This, however, requires an additional step such as positioning the mask.
In this case, the primer may be applied to the entire flat plate
including parts overlapping slits, and the positioning may be performed
after attaching the members and before curing. Additionally, in this
case, it is preferable to control the curing time by adjusting the primer
concentration and the peroxide concentration in advance. In the case that
the primer is applied to the entire surface of the flat plate, light
irradiation is not necessary, but the area to which the primer is applied
may be irradiated with light to avoid a color change of the resin, which
is caused by a light absorber dispersed in the resin depending on its
absorption wavelength, and therefore to improve the light transmissivity.

[0139] FIG. 15 is a view schematically illustrating a mechanism of another
three-dimensional display panel. The three-dimensional display panel 80
shown in FIG. 15 is a liquid crystal display panel including a pair of
transparent substrates 81 and a liquid crystal layer between the
transparent substrates 81. The liquid crystal layer between the
transparent substrate 81 is sealed with the seal 84. Additionally, light
blocking layers 82 are provided between the transparent substrates 81,
and the light blocking layers 82 are located at certain intervals
therebetween when viewed in a cross-sectional view.

[0140] In some three-dimensional displays, the liquid crystal display
panel 80 may be disposed as shown in FIG. 15 to produce three-dimensional
images. In these cases, three-dimensional images are produced by
adjusting light such that light passing parts and light blocking parts
are formed in a stripe pattern. Since light blocking layers are not
members actually existing in the display region, the resin composition
can be cured with light that is not controlled for three-dimensional
imaging. However, the seal 84 adhering the transparent substrates 81 of
the liquid crystal display panel 80 is opaque in some cases, and thus,
the liquid crystal display panel 80 for three-dimensional imaging may
include a light blocking part along the periphery thereof. In such a
case, the present invention allows the area that is prevented from being
exposed to light by the seal 84 to be cured by applying the primer to the
area. This type of three-dimensional display is widely used in mobile
devices such as mobile phones, smart phones, and tablet PCs, and the
liquid crystal display panel (display device) 70 for displaying images
thereon and the liquid crystal display panel (flat plate) 80 for
displaying slits (three-dimensional imaging) are attached to each other.
The liquid crystal display panel 80 for three-dimensional imaging may be
disposed in front of or behind the liquid crystal display panel 70 for
displaying images. The above three-dimensional display technique using
the above-described liquid crystal display panel allows for
three-dimensional imaging viewable with naked eyes.

[0141] Additionally, the flat plate is not limited only to
three-dimensional liquid crystal display panels as described above, and
may be a functional device such as a touch panel. A touch panel as
described in embodiment 3 may be disposed between the liquid crystal
display panel for displaying images and the liquid crystal display panel
for three-dimensional imaging. Thus, the adhesion technique using the
resin of the present invention is useful for members including a light
blocking part that may prevent an area behind the light blocking part
from being photocured.

Evaluation

[0142] The following description is offered to illustrate the components
and property values of samples prepared using the method of embodiment 1
(combination of photocuring and curing using a primer) as examples of the
cured resin layer of embodiment 1. Table 1 shows the compositions of the
samples of Examples 1 to 7. Table 2 shows the components and property
values of the samples of Examples 1 to 7 and Comparative Example.

[0143] All percentages "%" are % by mass relative to 100% by mass of the
whole resin composition in Table 1. The values for the oligomer, monomer
A, monomer B, monomer C, peroxide A, peroxide B, and photopolymerization
initiator are the amounts thereof based on part by mass.

[0145] The component of the primer of Table 2 is vanadium pentoxide
complex. The value 1/1 of the primer concentration means that the primer
was not diluted, and refers to a primer (AT QUICKA VE3, TOAGOSEI CO.,
LTD.), the primer component (vanadium pentoxide complex) concentration of
which was 3% by mass of the whole. The value 1/2 of the primer
concentration means that the primer was diluted to a 1/2 concentration,
and refers to a primer, the primer component concentration of which was
1.5% by mass of the whole. The value 1/10 of the primer concentration
means that the primer was diluted to a 1/10 concentration, and refers to
a primer, the primer component concentration of which was 0.3% by mass of
the whole. The solvent used for dilution was ethanol.

[0146] As shown in Table 2, the compositions shown in Table 1 could be
prepared into a favorable cured resin layer by the production method of
embodiment 1. In contrast, a cured resin layer prepared only by light
irradiation from the flat plate side without using a primer (Comparative
Example) was not good because it was not sufficiently cured.

[0147] FIGS. 16 and 17 are graphs of adhesion strength vs. time. FIG. 16
shows the results of the case in which the primer concentration was not
diluted, and FIG. 17 shows the results of the case in which the primer
concentration was diluted to 1/10. The graphs of FIGS. 16 and 17 are
based on the data of Tables 3 and 5, respectively. Tables 4 and 6 show
the relationship between the reactivity of the peroxide and time. Table 4
shows the results of the case in which the primer concentration was not
diluted, and Table 6 shows the results of the case in which the primer
concentration was diluted to 1/10. All percentages "%" of the peroxide in
Tables 3 to 6 and FIGS. 16 and 17 are % by mass relative to 100% by mass
of the whole resin composition.

[0148] Regarding the change of the adhesion strength against the peroxide,
the adhesion strength reached saturation after three hours when the
peroxide concentration was 0.3% by mass or higher, as shown in Tables 3
and 4. Tables 3 and 4 also reveal that when the peroxide concentration
was 1.0% by mass, all the adhesion strength values were highest, and were
thus the optimum values. This is presumably associated with dispersion of
the primer. When the amount of the peroxide is small (specifically 0.1%
by mass or less), the polymerization reaction does not sufficiently
proceed due to shortage of the peroxide even though the primer is
dispersed. When the amount of the peroxide is excessive (specifically
2.5% by mass or more), the polymerization reaction proceeds before the
primer sufficiently disperses due to too much peroxide. Therefore, too
much primer is consumed in the initial stage of dispersion, and only a
smaller amount of the primer is dispersed widely. The adhesion strength
values were regarded as good when they were 4 N/mm or higher.

[0149] As shown in Tables 5 and 6, when the primer concentration was
diluted to 1/10, the adhesion strength values were lower than those
obtained in the case that the concentration was not diluted. The
reactivity at the peroxide concentrations of 1.0% by mass or higher
exceeded 90% after 6 hours, and the reactivity at the concentration of
0.3% by mass or higher reached 90% or higher after 12 hours. This does
not mean that the reaction did not sufficiently proceed, but indicate
that slower polymerization results in lower adhesion strength.

[0150] Consideration of the results including the results of Tables 3 and
4 as well revealed that there is a relationship between the primer and
peroxide concentrations and the starting point of increase in adhesion
strength, and some of the combinations are suitable for the starting
point of increase in adhesion strength. In the case of no dilution and a
peroxide concentration of 0.3% by mass or higher, three hours were enough
to provide sufficient adhesion strength. Practically, the time period
required to achieve a practical level of adhesion strength is preferably
about three hours based on a consideration of the time period for the
alignment after the attachment, the interval until the alignment, and the
need of peeling in the case that rework becomes necessary after the
alignment.

[0151] Accordingly, when the primer concentration is not diluted, the
curing rate achieved at the peroxide concentration of 2.5% by mass is too
high, and may make it impossible to rework.

[0152] On the other hand, when the primer concentration is low,
specifically diluted to 1/10, the peroxide concentration should be
adjusted to 0.3 to 0.5% by mass. If the concentration is out of the
range, it takes too long a time to achieve a sufficient adhesion
strength, and such a concentration is not suitable for practical
production.

[0153] Application of the primer can be accomplished with a brush or a
dispenser, or by printing or the like. The concentration of the primer is
not always uniform over the whole coating, and the peroxide concentration
preferably falls within the range of 0.3 to 1.5% by mass, and more
preferably 0.3 to 0.5% by mass based on a consideration of dilution to
1/10.

[0154] The present application claims priority to Patent Application No.
2011-008175 filed in Japan on Jan. 18, 2011 under the Paris Convention
and provisions of national law in a designated State, the entire contents
of which are hereby incorporated by reference.